The map shows the mean annual concentrations of ammonium (NH4+), expressed as milligrams of NO2-N per litre of water, observed in groundwater monitoring stations and reported by EEA member countries via WISE. The purpose of the map is to provide an overview of the mean annual value of ammonium in groundwater across Europe and to enable the user to compare values per country or per groundwater body, depending on the scale of visualisation. Historical data since 2000 can be displayed using the time slider, and different horizons can be selected using the layers menu.

The map shows the mean annual concentrations of nitrites (NO2), expressed as milligrams of NO2-N per litre of water, observed in groundwater monitoring stations and reported by EEA member countries via WISE. The purpose of the map is to provide an overview of the mean annual value of nitrites in groundwater across Europe and to enable the user to compare values per country or per groundwater body, depending on the scale of visualisation. Historical data since 2000 can be displayed using the time slider, and different horizons can be selected using the layers menu.

The map shows the mean annual concentration of nitrates (NO3), expressed as milligrams of NO3-N per litre of water, observed in groundwater monitoring stations and reported by EEA member countries via WISE. The purpose of the map is to provide an overview of the mean annual value of nitrates in groundwater across Europe and to enable the user to compare values per country or per groundwater body, depending on the scale of visualisation. Historical data since 2000 can be displayed using the time slider, and different horizons can be selected using the layers menu.

The map shows the location of the water quality monitoring stations reported by EEA member countries via WISE SoE reporting. The purpose is to provide an overview of the spatial distribution and density of monitoring stations per water body category: rivers (including canals), lakes (including reservoirs), groundwater, and transitional, coastal and marine waters. The map displays all stations ever reported since 1992, so not all are currently active.

The data series are calculated as the average of annual mean concentrations for groundwater bodies/river stations/lake stations in Europe. Only complete series after inter/extrapolation are included (see indicator specification). The number of groundwater bodies/river stations/lake stations included per country is given in the notes below the individual substance charts.